One of my favorite costume projects was being vampires without coming out & saying we were vampires. Here is the costume (based on store-bought patterns, highly modified):
http://www.starkmadness.com/photos/a...s/10001/31.jpg
Mine was pretty simple, since I just added the red spider-web fabric, fake shirt sleeves, & trim (and scalloped the shoulders & waist). The tights are store-bought. Oh, and I made the boots, but you can find ones like those at a Renn Fair shop.